Michael J. Fox was 17 in Letters from Frank when he played the character 'Ricky'.
That was over 44 years ago in 1979.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 62, and has starred in 69 movies in total, 68 of those since Letters from Frank was released.
In Letters from Frank, I think Michael J. Fox looks: